Operation of a fuel cell stack assembly requires that the fuel gas be evenly distributed equally to all of the fuel cells in order to avoid fuel starvation. This has historically been accomplished using fuel distribution manifold devices within the fuel inlet manifolds having layers of evenly splitting the fuel flow into two flows, such as four layers, ending with 16 fuel inlets.
In order to achieve maximum efficiency of a fuel cell power plant, there is a need to recycle the anode exit gas back to the inlet of the anodes in order to extract the still usable fuel in the anode exhaust. Typically, this has historically been accomplished using an external hydrogen recycle blower and external plumbing. Ejectors have been used in which fresh fuel at the motive input provides the suction to draw recycle fuel into the suction inlet of the ejector.
Compared to external fuel inlet manifolds, internally manifolded fuel cell stacks offer benefits including lower cost, lower manufacturing time, minimized complexity, etc. External manifolds are used, especially at the anode, to accommodate large inlet fuel distribution devices, to achieve even reactant distribution to all of the cells. Achieving even distribution becomes difficult when dealing with internal manifolds. Utilizing a high pressure drop device provides the necessary even distribution, but high pressure devices limit the use of available anode exhaust recycle devices.